Method and apparatus for feeding sheets



June 21, 1949.

Filed Oct. 11, 1945 R. T. CHATTERTON 2,474,141

METHOD AND APPARATUS FOR FEEDING SHEETS 4 Sheets-Sheet 1 7 ygVENTOR.iz/M190? I ATTORN aY's June 21, 1949. R. .T. CHATTERTON 2,474,141

METHOD AND APPARATUS FOR FEEDING SHEETS Filed 001' 11, 1945 4Sheets-Sheet 2 IN V EN TOR.

ATTORN Ys June 21, 1949. R. 1'. CHATTERTON METHOD AND APPARATUS FORFEEDING SHEETS 4 Sheets-Sheet 3 Filed Oct. 11, 1945 u JNVENTOR. M525Juan/1Q ATTORNEYS June 21, 1949. 1', CHATTERTQN 2,474,141

METHOD AND APPARATUS FOR FEEDING SHEETS Filed Oct. 11, 1945 4Sheets-Sheet 4 L. Ez' .4 IZI I e Z 5/ K I 5 7 5 F A 5o IZI F mo -INVENTOR. djwfifimaw Patented June 21, 1949 METHOD AND APPARATUS FORFEEDING SHEETS Robert T. Chatterton, Chappaqua, N. Y., assignor toAmerican Can Company, New York, N. Y., a

corporation of New Jersey Application October 11, 1945, Serial No.821,697

The present invention relates to the individual feeding of sheets ofmetal by passage through a magnetic field constituting a zone ofseparation and has particular reference to a method and apparatus whichutilizes a plurality of magnetic areas of different magnetic strengthsthe nature of the magnetic flux in the areas being such as to cause thesheets to move under magnetic propulsion and in separated relation oneto the other, thus insuring the feeding of only a single sheet at onetime.

The present invention contemplates the feeding of sheets such as areused in great numbers by can manufacturers preferably from a stack. Fromthe stack the sheets pass through a field or zone comprising a pluralityof magnetic areas of separation of diflerent or varying magnetic forcesso that a sheet upon entering the area of lesser force becomesmagnetized and moves into an area of greater magnetic flux density andthis continues progressively the sheet thus passing from area to area.During such passage reluctance gaps are utilized in a manner whichseparates the sheets one from another while in the separation zone.Being thus definitely separated one from the other only a single sheetis fed after passage through the magnetic areas of the separation zone.

An object of the invention is the provision of a method Of and apparatusfor feeding sheets one at a time by introduction of the sheets into oneof a variety of magnetic areas or strata so that the magnetized sheetswhen unrestricted pass into the next adjacent field and so on throughoutthe separation zone,;removal of but a single sheet from the magneticareas thus being assured at all times.

Another object of the invention is the provision of a method of sheetfeeding in which reluctance gaps are maintained laterally of the stackof the sheets during their passage through the magnetic areas suchreluctance gaps having less flux density than the flux density in thesheets with the result that adjacent sheets do not closely approach eachother but are held in separated positions throughout the separationzone.

Yet another object is the provision of a method of sheet feeding inwhich the magnetic separation field or zone includes a plurality ofmagnetic areas or strata of uniformly increasing strength from oneboundary of the zone to the other, the various areas fanning out onerelative to the other so that the weakest magnetic area is always inwardof the point of feeding the 25 Claims. (Cl. 271-18) outermost separatedsheet and the outermost or strongest magnetic area or stratum is at anangle to said weakest area, thereby insuring that the outermost sheet orthe sheet closest to the point of feeding is always in the most suitableposition for removal from the magnetic field.

Another object of the invention is the provision of an apparatus forsheet feeding from a stack of magnetizable sheets having spaced magnetsfor setting on a magnetic field or zone of sheet separation in whichthere are a plurality of layers of magnetic areas the inner faces orstack facing sides of the magnets being inclined or at an angle to thestack to impart varying strengths of magnetic flux effective in thedifferent magnetic fields.

A further object is the provision of such an apparatus in which magnetsare located on three sides of the zone of separation there being opposedside magnets on two of the sides and one or more intermediate magnets onthe third side, all of the magnets having their bottom edges in ahorizontal plane and the side magnets being wedge shaped or inclinedalong the top relative to the plane of the unseparated sheets in thestack. this construction imparting a fan shape to the various resultingmagnetic areas of strata in the sheet separation zone, each magneticarea being at a slight angle to the area adjacent with the greaterthickness of each area in the magnetic zone adjacent the intermediatemagnet which assists in supporting the edges of the sheets adjacent itto maintain each sheet in a substantially fiat condition so that thetopmost sheet in being fed from the zone of separation is sufiicientlyelevated to clear all other sheets in the separation zone and to avoidstriking any machine parts during the removal of the sheet.

Another object of the invention is the provision of a sheet feedingapparatus of the character described in which the sheets are guidedbetween non-magnetic members and all sheets are aligned against one ofthe members during passage between the guides, the non-magnetic guidesalso keeping the sheet edges away from the magnets thus setting up thereluctance gaps for each sheet which function to keep the sheetsseparated while within the separation zone.

Still another object is the provision of a sheet feeding apparatus inwhich a stack of sheets is gradually lifted on an elevator and the stackis constantly centralized relative to the magnetic areas or strata inthe separation zone and sheets on the top of the stack are introducedinto the bottom of the zone of separation in synchronism Numerous otherobjects and advantages of the invention will be apparent as it is betterunderstood from the following description, which, taken in connectionwith the accompanying drawings, discloses a preferred embodimentthereof.

Referring to the drawings:

Figure 1 is a plan view of an apparatus for separating sheets of metalfor feeding in accordance with the steps of the method and embodylngapparatus of the present invention;

Fig. 2 is a rear view of the apparatus illustrating sheets carried ontop of a stack passing through a magnetic field or separation zonepreparatory to feeding;

Fig. 3 is a side elevation of the apparatus illustrated in Fig. 1 asviewed from the left hand side of that figure;

Fig. 4 is a longitudinal section taken substantially along the line 4-4in Fig. 1 and drawn to an enlarged scale;

Fig. 5 is an enlargedtransverse section taken substantially along theline 5-5 in Fig. l; and

Fig. 6 is a diagrammatic view showing generally in plan the action ofthe separation magnets and the magnetic lines of force as effective inthe separation zone.

In the drawings of the present invention one type of apparatus isdisclosed as being adapted to the feeding of sheets of metal a such astin plate or the like, from a stack b. The stack of sheets is preferablydeposited upon an elevator A (Fig. 2) such a stack being held upon theusual skid or platform B used in plants of the can manufacturer. Theelevator is designed to gradually and uniformly lift the stack of sheetsduring the operation of the apparatus.

At the top of the stack there is disposed a space C which constitutesthe magnetic field or zone of separation. On three: sides of this spaceare positioned magnets D for creating the magnetic lines of force withinthe separation zone C.

The magnets, which are preferably electromagnets but may be permanentmagnets, are preferably formed with cores or poles of solid block formsufficient in length to extend along a, substantial part of three of theedges of the sheets as they are positioned in the stack. In thispreferred embodiment the magnet cores are surrounded by magnetic coilsE. When the coils are energized the magnetic fiux flows from the polesof the magnets into the solid load of sheets on the top of the stack band this attracts a number of sheets causing the same to rise within thezone of separation C. These sheets position themselves in the magneticzone in such a manner that each sheet becomes saturated to a certaindegree and in this magnetized condition moves through the zone ofseparation.

The upward movement of the sheets from the stack through the magneticfield or zone of separation when a sheet is removed results from theincreased magnetic fiux density created in the top portion of themagnetic field just vacated by the removed sheet. The sheet which wasjust below the removed top sheet, is attracted into this vacated area ofincreased fiux density. This causes an increase in flux densityimmediately below thereby causing the next lower sheet and likewise eachsucceeding lower sheet to rise in the magnetic zone. The top sheet inthe stack 17 of unseparated sheets thus enters the zone by leaving thestack. The result of such action is the maintenance of a substantiallyconstant flux density at all times in the magnetic field.

The final positioning of the sheets in the zone of separation isdetermined by the inner faces of the magnets being inclined from thevertical. This provides a greater distance for the lines of magneticflux passing between magnets of opposite polarity with the result thatthe zone of separation may be considered as consisting of a plurality ofareas or strata F which have diiierent magnetomotive forces. Obviouslysince the shorter distance between magnets D for the conduction of themagnetic flux is at the top of the zone of operation, the area at thetop is at the maximum of magnetomotive force. thereby causing thetopmost sheet to always lie substantially in the plane of the top edgesof the magnet poles for removal by the feeding means.

The number of sheets which rise in the magnetic field depends on thedegree of saturation required to overcome the force of gravity.Provision is also made for preventing the edges of the sheets cominginto contact with the faces of the magnets. This is done by means ofnonmagnetic guides or spacing'members G which create a number of airgaps 0 (Figs. 4 and 5) between the sheet edges and the magnets. Eachsheet absorbs large amounts of flux from the air gap between it and themagnet pole and this causes a centering of the sheet a in the magneticzone C.

This air gap 0 between the sheet edge and the magnet is effective as areluctance gap for each individual sheet and the flux density in thespace will be less than that within the sheets. The effect of this is toseparate adjacent sheets and to prevent them from approaching tooclosely together. This therefore provides a definite separation of eachindividual sheet while it is in the separation zone.

At the time the sheets within the separation zone are rising intosuccessive magnetic areas of greater flux density provision is made foruniformly aligning the sheet edges irrespective of slight differences indimension of the sheets. This is done'by causing all of the sheets toengage against one of the non-magnetic guides G at one side of thesheets within the separation zone. The left hand guide G as shown inFig. 2 is the aligning guide of the apparatus shown.

The rear or intermediate magnet D which is located along the third sideof the sheets within the separation zone is effective in supporting thecenter of each sheet. In the event that the sheets are of only smalldimension such a third mag-net may be eliminated but for ordinary sheetfeeding as found necessary in a manufacturing plant, a third magnet isutilized to keep the sheets as flat as possible and thus minimizesagging or bending.

Since the fourth sides of the sheets at the edges do not have magneticseparation, these substantially unmagnetized edges will come together.To better support these edges of the sheets the various magnetic areasor strata within the separation zone are so arranged as to be slightlyout of parallel. In other words there is a fiaring out or fanning out ofthe various areas. The unmagnetized edges of the sheets may rest on theunseparated sheets in the stack below the zone of separation C. Fig. 4shows this position. Off-center or at the sides of these edges, thesheets may be slightly separated by the side magnets.

In order to accomplish this fanning out of the sheets, the side magnets,which it will be recalled, are disposed opposite one another along thetwo sides of the sheet, are wedge shaped. This means that the topsurfaces of the magnets are in an inclined plane (Fig. 3). All of themagnets at the bottom are in the same horizontal plane. Thus it will beseen that by reason of the resulting wedge shape with its inclined uppersurfaces of the two side magnets, that the topmost magnetic area and theadjacent areas below are at an angle to the horizontal.

The high side of the topmost area is located along the intermediatemagnet. All of the intervening magnetic areas between the top area andthe bottom are fanned out. This follows, by reason of the inclined innerfaces oi the magnets forming the air gaps c. The strongest air gaps areat the top and the bottom or lowermost air gap is the weakest. Sincethree edges of each separated sheet are supported by the magnetic field,and the fourth edge is held virtually flat by reason of its contact withthe sheet immediately beneath, the whole sheet is maintained in asubstantially flat or unbowed position. It is important that theseparated sheets be flat, since if they are not, they flatten out whenengaged and lifted by feeding devices such as suction cups, and thusstrike against the non-magnetic guides.

In order to further separate the rear edge of the topmost sheet from therear edge of the sheet directly beneath at the time of removing a sheetfrom the zone and also to elevate the sheet slightly above the rearmagnet as it is being fed, supplemental lifting devices J (Figs. 1' and3) are used. These devices may take the form of suction cups which isthe embodiment shown in the drawing and described in the specification.This further lifting of the rear edge of the topmost sheet takes placejust prior to removal of the sheet from the zone of separation C. Thisinsures against any engagement of adjacent sheets and insures againstthe topmost sheet striking the machine parts at the time it is beingfed. This is particularly useful where the sheets have beenlithographed, as a lithographed surface is more vulnerable to scratches.With some sizes and types of sheets the lifting devices J need not beused;

It will be seen that an important novelty in this sheet separation,different from previous separating devices utilizing magnetic fields, isthat the actual separation is caused by reluctance gaps c imposed oneach sheet. According to th present arrangement if the magnetomotiveforce of the coils E associated with the magnets is increased, the fluxdensity of the air gap will increase and the sheet separation will bereduced.

In adapting the reluctance gap separation principle to high speedproduction of sheet feeding as in the instant invention, provision ismade for engaging the top sheet in the zone of separation andwithdrawing it away from the third side on which the rear magnet islocated. This is illustrated as suction cup feeding devices K whichengage the forward or lower edge of the topmost sheet and draw itoutwardly between the side magnets inserting it into constantly rotatingfeed rollers L (Fig. 3) which transfer it from the zone of separation.Since the same magnetic force is continuously applied to the magnetsduring operation of the apparatus, the removal of a sheet at the top ofthe zone of separation has the effect of causing all of the floatingsheets within the zone to move up one space. This opens up a space for anew sheet which passes into the bottom of the zone from the stack.

i A preferred embodiment of the invention as disclosed in the drawingscomprises an apparatus, the principal parts of which are indicated inmore or less detail in Figs. 1 to 5, inclusive. Vertical frames 2|constitute supports for the elevator and other feeding parts of themachine. These fram supports are tied together at the top by a front bar22 and by a rear bar 23. At the bottom the frames 2| may be bolted tothe floor by angle irons 24.

The skid B is loaded with plate in the usual maimer. The loaded skid isthen brought into position for insertion into the apparatus by a truckor other conventional sheet delivering device. Such a truck as well asthe elevator device of the present invention are similar to that shownand described in the H. W. Lindgren United states Patent 2,375,241,granted May 8, 1945, on Sheet stacking machine.

The skid of sheets is pushed into the open back of the apparatus inbetween the two rear upright frames 2| and is deposited on a floatingplatform 25 (Figs. 2 and 3) of the elevator A. By using the termfloating it is intended to convey that the platform can be shiftedslightly in any direction. Rollers 26 which are carried in side channelirons 21 mounted on the platform 25, support the load and permit easyplacing of the skid and th stack of sheets onto the platform. In movingthe skid of sheets into the elevator, front bars 28 form a limiting stopfor the front edge of the stack (Figs. 2 and 3). The bars 28 may besecured to the floor at the bottom and near the top are held on a crossbar 29 through the medium of connecting Z bars. The cross bar 29 isfastened to the forward upright frames 2|. At the top each front bar 28is secured to and supports a non-magnetic cap bar 30. The cap barextends in front of the magnetic zone 'of separation C and beingnon-magnetic has no attraction for the separated sheets. It is over thetop of this ,cap bar that the sheets are removed singly by the feedingdevice K as will be explained later.

Vertical chains 3| are secured to the platform and form the supportingelements for the load placed thereon. These chains extend to and operateover sprockets 32 mounted on horizontal sprocket shafts 33. There arefour 'such chains 3|, two on each side and the four sprockets arelocated adjacent the corners of the apparatus. Two sprockets 32 on eachside of the apparatus are mounted upon a single sprocket shaft 33 andthe two sprocket shafts are driven in suitable manner for lifting thestacks of sheets a gradually as the sheets are separated and are fed bythe apparatus. Shafts 33 are journaled in bearings 34 carried in sidebars secured to the upright frames 2|. A connecting cross shaft 35(Figs. 1 and 3) extends at right angles to and beneath the sprocketshafts 33 and provides a connecting drive between the two sprocketshafts. Such a connecting shaft is joumaled inside bearings 36, 31carried indirectly in the forward upright frames of the apparatus. Thedrive connection between the two shafts 33 and the shaft 35 is made by aworm gear 38 on each sprocket shaft and thetwo worm gears mesh withworms 7 33 carried on shaft 35. For the purpose of the present inventionshaft 35 may be considered as the drive shaft for the elevator.

Anon-magnetic frame-surrounds and is secured to the four vertical frames2| and provides indirectly for a support for the magnets D. Such a frameis formed by two side bars 4| (Figs. 1, 2 and 3), a front bar 42 and arear bar 43. These bars are formed of non-magnetic material such asbrass and provide an insulation between the frame of the machine and themagnets. The side bars 4| directly support the bearings 36, 31

' at the front of the machine so that the drive shaft 35 is retained inits proper driving position on the upright frames. These bars 4|, 42 and43 are located just beneath the shaft 35 (see Figs. 2 and 3) and arefurther below the sprocket shafts 33.

A cross plate 45 (Fig. 1) extends across and is mounted on top of theside bars 4| this plate being substantially in the center of the sheetspace of the elevator A. A transverse plate 46 is secured to the centerof the plate 45 and extends back over the top of the rear bar 43. Theseplates 45, 43 are of magnetic material such as steel and provide asliding support for the magnets D and also form a. path for magneticflux, as will be fully explained later. Being carried on the insulatingframes 4| and 43 they, together with the immediate magnet parts, aremagnetically insulated so that the elevator A and supporting parts arenot magnetically charged.

The rear or intermediate magnet D is best illustrated in Figs. 2 and 4and includes a pole .piece or block which is carried on the lower 1 endof a core 52 which extends through the rear magnet coil E. Above thecoil the core passes into and is supported by a sliding member 53 whichis mounted upon the plate 43. The sliding member is formed with anupstanding lug 54 through which passes a horizontally disposed threadedshaft 55.

Such a shaft extends through and has rotation within a bracket 53 (seealso Fig. 3) resting on the rear bar 43. Outside of the bracket 56, theshaft ,55 is formed with a squared head 51 by means of which the shaftcan be engaged and rotated as by a suitable wrench. Upon rotation of thethreaded shaft the sliding member 53 is caused to move toward or awayfrom the center of the machine. This locates the rear magnet at theproper position relative to the stack of sheets being separated in thedevice.

Each side magnet D (Figs. 3 and 5) includes a pole piece or block 3|which is carried on the lower end of a core 62 which extends through thecorresponding magnet coil E. Each core above its magnet coil isconnected to a sliding member 33 which is slidably mounted upon thecross plate 45. The two sliding members 33 are equally and adjustablyspaced from the center of the apparatus so that the magnets carriedthereby at all times are positioned in proper relation to the side edgesof the sheets passing into the magnetic zone of separation C.

Each sliding member 63 is formed with an upstanding lug 64 through whichpasses an adjustment shaft 35. Such an adjustment shaft is provided withthreaded sections 33 the threads of which-are disposed in oppositedirections and each threaded section rotates within and has threadedengagement in the lugs 34 of the corresponding sliding member 33.

The adjusting shaft 65 extends across the machine and is iournaled forrotation in side brackets 31 (Figs. 1 and 3) which are resting on eachside of the side bars 4|. The two ends of the shaft 33 extend out beyondthe respective brackets 31 and each end is formed with a square head 33.By this means the adjustment shaft may be rotated in the desireddirection from either side of the machine by application of a wrenchonto either head section 63. Thus it will be seen that this constructionof a common shaft for both side magnets insures th the side magnets willat all times be centered in any adjustedpositlon relative to the centerof the machine.

The magnet block or pole piece 5| of the intermediate magnet, as bestshown in Fig. 4, is tapered on its inner face as by an inclined surfaceII. This tapered construction provides the air gap 0 for the rearmagnet, as already fully described.

The non-magnetic guide G of the rear magnet is formed from sheetmaterial with a series of walls. This includes a slightly off verticalwall section 12 terminating at the top in a rounded edge 13. At thebottom this wall part merges into an angular or tapered wall part 14which extends into a horizontal wall 15. This non-magnetic guide issecured to the pole piece 5| through the medium of a non-magnetic spacerplate 13.

Such a guide is formed of non-magnetic material such as stainless steeland its construction provides for the proper locating of the sheets alongitudinally while in the magnetic zone of separation C. The inclinedsurface 14 of the guide insures the proper and continuous centering ofthe stack b as it rests on its floating platform 25 and insures properguiding of a sheet leaving the top of the stack as it is being lifted bythe elevator A. The wall section 12 assists in aligning the edges of thesheets adjacent the intermediate magnet while in the magnetic areas F.

Owing to the inclined face 1| of the pole piece 5|, a uniformlydecreasing separation is had between the edges of the sheets and theface of the magnet extending from the top of the stack and upwardly intothe magnetic field or zone C. This magnet construction which is presentin all of the magnets effects the different magnetic strengths in theuniformly increasing magnetic areas F starting from the bottom andapproaching the top maximum strength field.

The side magnets D (Fig. 5) are formed in a similar manner to theintermediate magnet and each side magnet has its own non-magnetic guideG. The magnet pole piece 3| is formed with an inclined inner face 8|.Its non-magnetic guide consists of a slightly off vertical wall section82 terminating at the top ina flared edge 83. At the bottom this wallpart merges into an inclined wall 34 which extends into a lowerhorizontal wall section 85. This non-magnetic guide G is secured to thebottom of the magnet pole piece 6| through the medium of a, non-magneticspacer plate 83.

The magnet D to the right (Fig. 5) is of similar construction andconsists of a pole piece or magnet block 3| having an inclined innerface 32. The non-magnetic guide G for this magnet includes a wall 93which is slightly off the vertical, this wall terminating at the top ina flared edge 34. At the bottom this wall part merges into an inclinedwall 35 which extends into a lower horizontal section 36. Thisnon-magnetic guide is secured to the magnet pole piece 3|, a nonmagneticspacer block 31 being provided for this purpose.

This right-hand magnet for many sheet feeding conditions may be the sameas that'on .the

left. However, it is sometimes desirable toali'gn one edge of the sheetswhile in the separation zone C and Fig. shows one way of doing this.This magnet is also formed with a sheet edge aligning unit consisting ofa finger 98; pivoted" at 99 in.

the spacer block 91. This finger is urged inwardly I against the righthand side edges of the" se1 at-v rated sheets within the. zone- .017separation 1G] by a spring I00. Spring Hill is seatedjin-a bore formedin the magnet pole piece ;9l vthe inner end of the spring pressing.against-the finger 98.

The inclinedwalls 84, 95'of..the guide members G for the two, 'sidemagnetpole pieoes 6|, 9|

insure the proper placing of the stack'of sheets as the upper 'part ofthe risingstack moves 'in between the side magnets. The walls 93am notparallel but are spread apart a slight 'dis-.' tance at the top. Thisconstructionremoves: any confinement on the side edges of asheet-apassing into the zone of separation C. The minimum spacing of thewalls 82, '93 at their. mergerwiththe inclined walls 84, 95 insuresunrestricted mag: netic action upon the sheets 'whiletw ithin themagnetic fields after each sheethas been properly centered. a

As'the rising and floating sheets in thezone plate 46 into the plate 45.It is at this point that there is a dividing of the path of travel, theflux passing both to the right and to the left toward both ends of theplate 45 and thence into the cores 620i the two side magnets. This com-.pletes the magnetic circuit as it is effective in the various magneticparts of the machine.

Thef-back lifting devices J engage the topmost sheet adjacent itsrear'edge in two spaced regions. This insures a greater separation ofthe rear. edgeof the topmost sheet a from the sheet rbelow'and thisminimizes scratching of the sheets as a, sheet is being fed from themagnetic separation zone. Such lifting devices tend to unhook anybentedge sheets which otherwise may look together. Since movement of thedevices is .relatively rapid the resulting vibration of the spread apartsheets in the zone insures more C approach the .top. each sheet. ispushed over toward the left hand magnet D and even though there isvariation in width of sheets, the separated sheets within the magneticareasfF'are aligned along one side and against the wall 82 of thenon-magnetic guide G on that side. The top floating sheet is thenready'for its lateral r'emovalby the feed rollers L over? the cap bar(Figs. 1, 3 and 4).

positive separation between sheets even though tion cup through the pipeH2 and the desired vertical movement of the suction cupis had inconventional manner. I

By means of the slight lifting of the topmost sheet adjacent the rearedge and intermediate 30, but before describing this: attention willf behad to the path of magneticfiux through the ma chine partswhich give themagnetic'zone of sheet separation C.

Different arrangements 'of the magnets .D'may be had in-order to providethe proper magnetic flux in the. magnetic areas F. .Figi 6 shows indiagram a schematic path of travel. of'the'm'ag netic flux through thesheet a: when""the', 'side magnets D are of the same polarity and-when.a

its width any tendency that the sheet may have of sagging in 'the middleis overcome. This --'presents a=-better' feeding position for the sheetand insures that the sheet will completely clear any mechanism connectedwith the magnets D or parts of the elevator A.

When the sheet is being brought into its raised position by the liftingdevices J, the front edge of the sheet is-engaged by a pair of suctioncups I 5 which form'a part of the suction cup feeding single rear orintermediate magnet-is used of a 7 different polarity. For example, theside magnets D'may-both be south magnet D is north.

This Fig. 6 also indicates the magne ic; hurr es" poles while the thirdidevices K. Two suction cups engage the sheet along its forwardjedge andlift it to a position above the cap bar 30. i The suction cups H5 thenmove forward carrying the sheet above the cap bar and inserting itsforward edge in the rotating being induced electrically for the magneticareas F as by passing an electric currenti'throughfall three magnetcoils E. Electrical-f energy maybe caused to flow along a plus wire din'to the" left side m'agnet'coil E energizing the leftside mag,

net. The current than passes'by way of a. wire e to the right sidemagnet coil E energizing-the right side magnet. From this magnetcoil'the' current passes by way of a wire f to the rearmagnet coil Ethusenergizin the rear. "magnet-1A wire 9 leading from the rear magnetcoil E'may be a minus wire the two wires d and g being con nected to asuitable source of electrical'current',

as shown in the drawing.

The path of the magnetic flux is'indicate'd by dotted lines in Fig. 6and follows two curved paths 7' in the zone of magnetic separation Cpassing from the two side magnets throughthe sheet a and into the rearmagnet-D. From the rear magnet this flux passes through the core 52 intothe steel'plate 46. For purposesfofillustration there is shown two armsof the plate 46 but it will be understood that in reality there is onlya single straight plate 46. 1

The magnetic flux passes from the end of the feed rollers L.

'Eachsuction cup H5 is carried on the lower end. of a pipe I IS. The twosuction cups I I5 and the associated pipes llfim'ay be of usualconventio'nalstyle and are supported and controlled in-a manner first toengage the forward edge of the topmost sheet in the zone of separationC. Then thesheet islifted vertically to the position shown in Fig. 3ofthe drawings. Following this the suction cups H5 move forwardsufiiciently to insert the front edge of the sheet into the feed rollersL. During this forward feeding movement gtherear part ofthe sheet willeasily slip along the holding faces of the suction cups Ill withoutbreaking the vacuum or if desired the vacuum can be cut off from thecups.

' Feed rollers L are two in number and are dis- '65 posed on shafts I'll(Figs. 1 and 3) arranged in vertical alignment one with the other. Theshafts l'2l are journaled in bearings. These bearings may be a part of aseparate machine into which the sheets are fed for further treatment.For example, the sheets may be introduced into a coating machine inwhich case the feed rollers L will constitute a part of the coatingmachine. The rollers and the shafts are rotated in any suitable manneras through proper gearing with the drive mechanism of the coatingmachine.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description, and it will beapparent that various changes may be made in the form, construction, andarrangement of the parts of the apparatus mentioned herein and in thesteps and their order of accomplishment of the process described herein,without departing from the spirit and scope of the invention orsacrificing,

all of its material advantages, the apparatus and process hereinbeforedescribed being merely a preferred embodiment thereof.

I claim:

1. The method of individually feeding stacked sheets of metal bytraversing a magnetic field of separation, which consists in maintaininga magnetic field by the introduction \of/varying degrees of flux fromspaced magnet poles to produce strata of magnetic flux in said fieldhaving a minimum flux density at one boundary of the field andincreasing to a maximum flux density at the opposite boundary,introducing the sheets into said magnetic field at the region of minimumflux density to magnetize the sheets so that they move toward the regionhaving the greatest flux density, and spacing the magnetized sheet edgesfrom said magnetic poles to create a reluctance gap for each sheet tocause separation of the sheets from one another while within the field.

2. The method of individually feeding stacked sheets of metal bytraversing a magnetic field of separation, which consists in introducingflux into said field from spaced poles, maintaining said flux insuccessive magnetic areas approaching horizontal positions in saidfield, each of said areas containing a reluctance gap between the polesand sheet edges, the reluctance gap of one area varying from that of anadjacent area, whereby said flux permeates said areas in layers ofvarying magnetic forces with the maximum force at the top, andintroducing horizontally disposed sheets into the lowermost of saidmagnetic areas to magnetize the sheets so that they separate and moveupwardly to the top of said field.

3. The method of individually feeding stacked sheets of metal bytraversing a magnetic field netic flux into said field from spacedpoles, maintaining in said field magnetic areas having diiferentmagnetic forces maintaining in each of said areas a reluctance gapbetween the poles and the sheet edges, said reluctance gap varyingbetween a maximum at one and a minimum at the opposite boundary of saidfield, introducing the sheets into said magnetic field at the boundaryof minimum flux density to magnetlze the sheets so that they separateand move toward the boundary of the field having the greatest density,and successively removing individual sheets from the maximum magneticarea as they are drawn into the same.

4. The method of individually feeding stacked sheets of metal bytraversing a magnetic field of separation, which consists in elevating astack of sheets with the sheets in horizontal position, introducinmagnetic flux into said field from spaced poles arranged at the edges ofthe sheets and producing superposed areas of flux adjacent the top ofthe stack-to magnetize the sheets and to effect their upward movementinto the magnetic areas of increasing magnetic forces, each of saidareas containing a reluctance gap between the poles and sheet edges, thereluctance gap of one area varying from that of an adjacent area thedenser flux layers of the magnetic field, up-

wardly decreasing reluctance gaps in said field separating adjacentsheets during their passage through the field, and successively removingthe top sheet at the time another sheet is presented to the bottom ofthe magnetic field by the elevation of the stack of sheets.

6. The method of individually feeding stacked sheets of metal bytraversing a field of magnetic areas of separation, which consists inproducing and maintaining said field as a number of superposed magneticareas of increasing magnetic forces from bottom to top of the field bythe introduction of magnetic flux from spaced magnet poles throughupwardly decreasing reluctance gaps,introducing the sheets into thebottom of said magnetic fieldto magnetize the sheets so that theyseparate, float and move up through the increasing magnetic flux of theareas, alignr of separation, which consists in introducing maging thesheet edges while the sheets are thus magnetized, and successivelyremoving individual sheets from the top of said magnetic field.

7. The method of individually feeding stacked sheets of metal bytraversing a field of magnetic areas of separation, which consists inelevating a stack of sheets with the sheets in horizontal position,maintaining said magnetic areas as angularly disposed layers of upwardlyincreasing magnetic forces adjacent the top of the stack by theintroduction of magnetic flux from magnet poles through upwardlydecreasing reluctance gaps arranged at opposite side edges and at anintermediate edge of the sheets to magnetize the sheets and cause themto separate and traverse the said magnetic layers, each sheet passingfrom a lesser to a greater magnetic area of force while floating from ahorizontal position into the upper portion of the field where it is atan angle to the unseparated portion of the stack, and removing thetopmost sheet in the field by shifting it laterally away from saidintermediate magnet pole and between said opposed side magnet poles.

8. In 'an apparatus for individually feeding stacked sheets of metal bytraversing a magnetic field of separation, the combination of spacedmagnet poles having opposed inclined faces for stacked sheets of metalby traversing a magnetic field of separation, the combination ofcooperating spaced magnets for maintaining the magnetic fieldtherebetween, said cooperating magnets being spaced further apart at thebottom of said magnetic field than at the top to create varying magneticforces within the field with the maximum force at the top, meansforintroducing horizontally disposed sheets into the bottom of saidmagnetic field to magnetize the sheets so that they move upwardly towardthe top of the field, a non-magnetic guide arranged adjacent each magnetfor spacing the magnetized sheet edges from said maghets to create areluctance gap for each sheet less than the flux density of the sheet tocause separation of the sheets one from another while within saidmagnetic field, and feeding devices for successively removing individualsheets from the top of said magnetic field.

10. In an apparatus for individually feeding stacked sheets of metal bytraversing a magnetic field of separation, the combination ofcooperating spaced magnets for maintaining the magnetic field the insidefaces ,of said magnets being tapered to provide a greater space betweenopposed magnets at the bottom than at the top so that magnetic flux fromthe magnets creates layers of varying magnetic forces within the fieldwith the maximum forces at the top, said opposed magnets also havinginclined upper surfaces 50 that said magnetic layers between magnetsform a fan-shaped magnetic field, means for introducing horizontallydisposed sheets into the bottom of said field to magnetize the sheets sothat they move upwardly from a layer of lesser to a layer of greatermagnetic force and from a horizontal position into an inclined position,non-magnetic guides arranged adjacent the tapered faces of said magneticpoles to prevent the sheet edges from engaging said magnets therebycreating reluctance gaps at the sheet edges to separate the sheets fromone another while within the field, and feeding devices for successivelyremoving iiidividual sheets from said top inclined position.

11. In an apparatus for individually feeding stacked sheets of metal bytraversing a magnetic field of separation, the combination ofcooperating spaced magnets for maintaining the magnetic field by theintroduction of magnetic fiux effective in the field as varying areas ofmagnetic forces, means for introducing the sheets into said magneticfield at an area of minimum fiux density to magnetize the sheets so thatthey have the tendency to move toward an area of greater dens ty, fixednon-magnetic guides located adjacent the magnets for spacing themagnetized sheet edges from said magnets to create a reluctance gaphaving a flux density less than the flux density in said magnetizedsheets to separate the sheets from one another while within the magneticfield. said guides having inner faces for correctly centering each sheetas it enters the magnetic field and being tapered to release thecentered sheet, and feeding devices for successively removing individualsheets from the maximum magnetic area as they are drawn into the same.

12. In an apparatus for individually feeding stacked sheets of metal bytraversing a magnetic field of separation, the combination of a sheetelevator for lifting a stack of sheets with the sheets in horizontalposition, cooperating magnets arranged at opposite sides and along anintermediate side of said stack, the bottom of said magnets being spacedfurther apart than the top for maintaining adjacent layers of varyingmagnetic force in said magnetic field adjacent the top of the stack,said elevator introducing a sheet from the top of the stack into thebottom of said stacked sheets of metal by traversing a magnetic field ofseparation, the combination of spaced magnets having opposed inclinedfaces for maintaining magnetic areas of varying magnetic forces in saidfield, means for introducing the sheets into said magnetic field so thatthe sheets are magnetized and move toward areas of the field havingincreasing magnetic force. non-magnetic guides secured to said magnetsand interposed between the sheet edges and the adjacent faces of themagnets for spacing the sheet edges from the magnets to create areluctance gap for each sheet and to separate the sheets from oneanother while within said field, spring means on One of said guides forlocating one edge of each sheet against the other of said guides as asheet enters the said field to control its position, and feeding devicesfor removing said located sheet from said magnetic field.

14. In an apparatus for individually feeding stacked sheets of metal bytraversing a magnetic field of separation, the combination of a platformfor holding a stack of sheets, spaced magnets of like polarity locatedon opposite sides of the sheets on said platform, a cooperatingintermediate magnet of opposite polarity located adjacent the rear ofsaid sheets, means for energizing said spaced and said cooperatingmagnets so that the lines of force passing through the magnets and intothe space between the magnets create layers of magnetic fiux, means formaintaining the said layers at different strengths of magnetic force,means for introducing sheets from the stack on said platform into themagnetic field layer of minimum magnetic force to magnetize the sheetsand cause their movement through the magnetic field, feeding devices forremoving the sheets singly from the layer of maximum magnetic force, andnon-magnetic guides for spacing the magnetized sheet edges from saidmagnets during the sheet movement through the magnetic field to createreluctance gaps for separation of admade weaker than said side magnets,means for energizing said magnets so that the lines of force passingbetween magnets of opposite polarity are effective as layers of magneticflux of different magnetic strength to cause movement of the sheetsthrough the magnetic field, non -magnetic guides for spacing themagnetized sheet edges from the magnets to create a reluctance gap forseparation of adjacent sheets while within said field, feeding devicesfor singly removing a separated sheet by withdrawing from said weakerintermediate magnet, and means for introducing sheets into said magneticfield as sheets are removed therefrom to insure maintenance ofsubstantially the same number of sheets in the magnetic field.

16. In an apparatus for individually feeding stacked sheets of metal bytraversing a magnetic field of separation, the combination of anelevator for maintaining the sheets in horizontal position while liftingthe same, a support located above said elevator, magnets carried by saidsupport and located in spaced relation on three sides of the sheets onsaid elevator, means for energizing said magnets to create layers ofmagnetic areas of separation above the stack of sheets the magnetic fiuxin said areas being at a minimum at the top of the stack and increasingfrom above that position in ascending order within the field tomagnetize the sheets as they are lifted into the field by said elevatorand to cause the same to rise through said magnetic layers, non-magneticguides for spacing the magnetized sheet edges from said magnets tocreate reluctance gaps for the sheets thereby separating the sheets fromone another while in said magnetic field, and means for adjusting saidmagnets on said supports to adapt the apparatus to the size of sheets onsaid elevator.

17. In an apparatus for individually feeding sheets of metal from astack by traversing a magnetic field of separation, the combination ofspaced magnets the bottom edges of the magnets being in a horizontalplane and their top edges being in an inclined plane for maintaining afan shaped magnetic field of separation, said magnets being angularlydisposed relative to said stack for uniformly increasing the magneticforces in said field extending in layers from bottom to top, elevatormeans for introducing horizontal sheets into the bottom horizontalmagnetic layer to magnetize the sheets so that they float and move upthrough the increasing magnetic flux of the layers and into the topinclined layer, non-magnetic guides for spacing the magnetized sheetedges from said magnets to create reluctance gaps for each sheet in thefield to separate the sheets one from another, and suction cups locatedabove the floating sheet in said )zop field for engaging and forremoving the top separated sheet.

18. In an apparatus for individually feeding stacked sheets of metal bytraversing a magnetic field of separation, the combination of spacedmagnet for maintaining a magnetic field of separation by theintroduction of magnetic fiux to produce varying magneticforces in thelayers of said field with the maximum force at the top, a sheet elevatorfor lifting the sheets into said magnetic field at the bottom layer ofminimum flux density to magnetize the sheets so that they move towardand into the top layer of greatest flux density, non-magnetic guides forspacing the magnetized sheet edges from said magnetic poles to createreluctance gaps having flux density less than the flux density in saidmagnetized sheets to cause separation of the sheets while within thefield, said guides having inclined opposite surfaces for centering thestack of sheets carried by said elevator entering said magnetic field,and suction cups for engaging and successively removing individualsheets from the top maximum magnetic layer.

19. In an apparatus for individually feeding stacked sheets of metal bytraversing a magnetic field of separation, the combination of spacedmagnets arranged on three sides of a rectangular area constituting themagnetic field of separation, the bottom edges of said magnets being ina common horizontal plane with the top edges of opposite side magnets inan inclined plane with the higher part adjacent the magnet on the thirdside, the inner faces of said magnets being inclined from the verticalwith the bottom edges enclosing a. larger rectangular area than that atthe top for creating a series of fan shaped superposed magnetic layersof varying magnetic forces, means for introducing sheets into the bottommagnetic layer of minimum flux density to magnetize the sheets so thatthey rise into upper layers of greater flux density, non-magnetic guidesarranged adjacent said magnets for spacing the magnetized sheet edgesfrom the magnets to create reluctance gaps for each sheet whereby thesheets are separated from one another while within the field, means forfurther lifting the higher end of a sheet when it reaches the topinclined magnetic layer, and feeding devices for reguiging said raisedtop sheet from said magnetic 20. In an apparatus for individuallyfeeding stacked sheets of metal by traversing a magnetic field ofseparation, the combination of spaced wedge shaped side magnets and acenter rear magnet arranged with their bottom edges in a horizontalplane for maintaining a lowermost magnetic layer of separation in ahorizontal plane and with the layers above uniformly fanning out to aninclined layer on top, means for progressively increasing the magneticforces in said layers to a maximum strength in the uppermost layer, asheet elevator located below said magnetic field for lifting a stack ofsheets to feed from the top of the stack horizontal sheets into thebottom of said magnetic field whereupon the sheets are magnetized andfloat up through the layers of increasing magnetic fiux of the field,said rear magnet holding up the center of the rear sheet edges tominimize bending of the floating sheets, non-magnetic guides fastened tosaid magnets for spacing the sheet edges from said magnets to createreluctance gaps for each sheet in the field to separate the magnetizedsheets one from the other, a front guide for the stack of sheets beinglifted by said sheet elevator, a non-magnetic tip on said guide, andfeeding devices located above the said field for engaging the lower endof the top sheet and for removing it from said magnetic field.

21. The method of individually feeding stacked sheets of metal bytraversing a magnetic field of separation, which comprises maintenanceof a magnetic field adjacent a magnetic pole and a stack of metal sheetsproducing strata of flux in said field varying between a minimum fluxdensity at one and a maximum flux density at the opposite boundary ofsaid field, introducing said stacked sheets into the stratum of minimumfiux density; and guiding said sheets through said strata and spacedfrom said poles to the opposite boundary of said field, said sheetsbeing separated in and moved through said strata by said magnetic flux.

22. In an apparatus for individually feeding stacked sheets of metal bytraversing a magnetic field of separation, the combination of aplurality of spaced magnets located adjacent three edges ofsubstantially rectangular magnetizable sheets arranged in a stack tocreate a magnetic field of separation in the outer portion of saidstack, each of the magnets adjacent two opposed edges of said sheetshaving an inclined outermost face disposed withone end of said facespaced farther than the other end from the plane of the outermostunseparated sheet in said of spaced sheet separator magnets locatedadjacent at least three spaced peripheral points of magnetizable sheetsarranged in a stack to create a magnetic field of separation in theouter portion of said stack, the stack facing side of at least one ofsaid magnets being at an angle to the respectively adjacent side of saidstack to create varying magnetic forces within said magnetic field ofseparation for separating said sheets a one from another to facilitateremoval of individual sheets from the outer portion of said stack. 24.An apparatus for individually feeding I stacked sheets of metal bytraversing a magnetic field of separation, comprising a sheet separatormagnet located adjacent a stack of magnetizable sheets to create amagnetic field of separation in the outer portion of said stack, thestack facing side of said magnet being at an angle to the respectivelyadjacent side of said stack to create varying forces within saidmagnetic field of separation which increase in strength towards theNumber Name Date 1,716,602 Ross June 11, 1929 1,870,314 Lincoln Aug. 9,1932' 2,341,639

18 outermost portion of said stack for separating said sheets one fromanother to facilitate positive removal of individual sheets from theouter portion of said stack.

25. The method of individually feeding magnetizable sheets from a supplyof such sheets arranged in a stack by traversing a magnetic field ofseparation providing a stack having its outermost sheets separated andfanned out in substantially triangular fashion at acute angles to itsinnermost and unseparated sheets, which method comprises creating aneffective zone of said magnetic field of separation at the outer portionof said stack, said zone having an outermost effective boundarysubstantially coinciding with the plane of the outermost separated sheetand an opposed innermost effective boundary substantially coincidingwith the plane of said innermost and unseparated sheets, introducingsaid unseparated sheets into said zone of separation through saidinnermost boundary of said zone, and successively removing individual,separated sheets from said outermost boundary of said zone.

' ROBERT T. CHATTERTON.

REFERENCES CITED The following referenlces are of record in the file ofthis patent:

UNITED STATES PATENTS Mathiesen Feb. 15, 1944

